When pain is not fully explained by organic lesion: a psychiatric perspective on chronic pain patients.

Recent literature demonstrates the relationship between psychopathology and medically unexplained pain, even if the results of several studies show a high degree of variability. The present study was planned with the aim of analysing both the possible relationship between the level (low/high) of organicity and the presence of psychopathology, and the degree to which these differences are related to methodological problems. Between 1998 and 2000, four hundred and thirty six consecutive patients seen at the Pisa Pain Therapy and Palliative Care Unit were requested to fill in a questionnaire, the GHQ-12, to screen the subjects probably with (GHQ-12>3) or without (GHQ-12</=3) psychopathology. All the patients scoring above the GHQ-12 threshold (score of 3), and a randomised sample of those scoring below the GHQ-12 threshold, were included in the study. These patients were then interviewed using three different instruments: the Mini International Neuropsychiatric Interview (MINI) for a standardised psychiatric diagnosis, the Semistructured Interview for Depression (SID) for the characterisation of temperament, and the Italian Pain Questionnaire (IPQ) for the evaluation of pain. Our results suggest that Somatisation Disorders are more frequent in the medically unexplained pain group than in the medically explained pain group, whereas the other psychiatric disorders have a similar prevalence in the two pain groups. Mood and anxiety disorders are correlated with high scores on GHQ-12 and medically explained pain has a higher prevalence of GHQ-12>3 than the medically unexplained pain group. These results confirm that methodology is an important factor that could modify results in psychiatric research. Both medically unexplained pain and the presence of psychopathology are significantly correlated with sex, and age: females and young patients have a higher prevalence of psychopathology and of medically unexplained pain. Our results suggest that in the correlation between the low organicity of pain and psychopathology, the age and sex play a relevant role.